N2 -naphthalenesulfonyl-L-argininamides and the pharmaceutically acceptable salts thereof

ABSTRACT

N 2  -naphthalenesulfonyl-L-argininamides and the pharmaceutically acceptable salts thereof have been found to be effective as pharmaceutical agents for the inhibition and suppression of thrombosis.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of application Ser. No.671,568 Mar. 29, 1976, which in turn was a divisional of applicationSer. No. 622,390 filed Oct. 14, 1975, abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the discovery of certain new and useful N²-naphthalenesulfonyl-L-argininamides and the pharmaceutically acceptablesalts thereof, which are of especial value in view of their outstandingantithrombotic properties and low toxicities.

2. Description of the Prior Art

In the past, there have been many attempts to obtain new and improvedagents for the treatment of thrombosis. The N²-(p-tolylsulfonyl)-L-arginine esters have been found to be one type ofagent which can be used and these have been found to be effective indissolving blood clots. (U.S. Pat. No. 3,622,615, issued Nov. 23, 1971).

One family of compounds which have been found to be particularly usefulas highly specific inhibitors of thrombin for the control of thrombosisis the N² dansyl-L-arginine ester or amide. (Our pending U.S.application Ser. No. 496,939, filed Aug. 13, 1974 now U.S. Pat. No.3,978,045).

However, there is a continuing need for a highly specific inhibitor onthrombin for the control of thrombosis, which exhibits lower toxicity.

SUMMARY OF THE INVENTION

It has now been discovered that N² -naphthalenesulfonyl-L-argininamidesexhibit antithrombotic activity and even lower toxicity levels at thesame relative potencies, as compared with the N² -dansyl-L-arginineester or amide. The compounds of this invention can be represented bythe formula (I): ##STR1## wherein R₁ is selected from the groupconsisting of naphthyl, 5,6,7,8-tetrahydronaphthyl and naphthylsubstituted with at least one substituent selected from the groupconsisting of halo, hydroxy, C₁ -C₁₀ alkyl and C₂ -C₂₀ dialkylamino; R₂is selected from the group consisting of C₂ -C₁₀ alkyl, C₂ -C₁₀alkoxyalkyl, C₂ -C₁₀ alkylthioalkyl, C₇ -C₁₅ aralkyl, C₃ -C₁₀ cycloalkyland C₄ -C₁₀ cycloalkylalkyl; R₃ is selected from the group consisting ofhydrogen, C₁ -C₁₀ alkyl, C₇ -C₁₂ aralkyl and C₆ -C₁₀ aryl; and n is aninteger of 1, 2 or 3. Also encompassed within this invention arepharmaceutically acceptable satls thereof.

This invention also relates to a method for inhibiting activity andsuppressing activation of thrombin in vivo, which comprises introducinginto a living body a pharmaceutically effective amount of an N²-naphthalenesulfonyl-L-argininamide or the pharmaceutically acceptablesalts thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This invention relates to a group of N²-naphthalenesulfonyl-L-argininamides of the formula (I): ##STR2##wherein R₁ is naphthyl, such as 1-naphthyl and 2-naphthyl,5,6,7,8-tetrahydronaphthyl, such as 5,6,7,8-tetrahydro-1-naphthyl and5,6,7,8-tetrahydro-2-naphthyl, or naphthyl substituted with at least onesubstituent selected from the group consisting of halo, such as fluoro,chloro, bromo and iodo, hydroxy, alkyl of 1-10 (preferably 1-5) carbonatoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl or thelike, and dialkylamino of 2-20 (preferably 2-10) carbon atoms, such asdimethylamino, diethylamino, N-methyl-N-ethylamino or the like; R₂ isalkyl of 2-10 (preferably 2-6) carbon atoms, such as ethyl, propyl,butyl, isobutyl, pentyl, hexyl, octyl, decyl or the like, alkoxyalkyl of2-10 (preferably 2-6) carbon atoms, such as methoxymethyl, ethoxymethyl,propoxymethyl, 2-methoxyethyl, 2-ethoxyethyl, 2-propoxyethyl,3-methoxypropyl, 3-ethoxypropyl, 3-propoxypropyl, 4-methoxybutyl,4-ethoxybutyl, 4-butoxybutyl, 5-butoxypentyl or the like, alkylthioalkylof 2-10 (preferably 2-6) carbon atoms, such as methylthiomethyl,ethylthiomethyl, propylthiomethyl, 2-methylthioethyl, 2-ethylthioethyl,2-propylthioethyl, 3-methylthiopropyl, 3-ethylthiopropyl,3-propylthiopropyl, 4-methylthiobutyl, 4-ethylthiobutyl,4-butylthiobutyl, 5-butylthiopentyl or the like, aralkyl of 7-15(preferably 7-10) carbon atoms, such as benzyl, phenethyl,3-phenylpropyl, or the like; C₃ -C₁₀ cycloalkyl, such as cyclopropyl,cyclopbutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl,cyclononyl, cyclodecyl or the like, or C₄ -C₁₀ cycloalkylalkyl, such ascyclopropylmethyl, cyclopentylmethyl, cyclohexylmethyl,2-cyclohexylethyl, cyclooctylmethyl or the like; and R₃ is hydrogen,alkyl of 1-10 (preferably 1-6) carbon atoms, such as methyl, ethyl,propyl, butyl, tertbutyl, hexyl, octyl, decyl or the like, C₆ -C₁₀ arylsuch as phenyl or naphthyl, and preferably phenyl, or aralkyl of 7-12(preferably 7-10) carbon atoms, such as benzyl, phenethyl or the like.

Suitable illustrations of R₁ in the above formula (I) are 1-naphthyl,2-naphthyl, 5,6,7,8-tetrahydro-1-naphthyl,5,6,7,8-tetrahydro-2-naphthyl, 6-methyl-2-naphthyl, 6-methyl-1-naphthyl,7methyl-1-naphthyl, 7-methyl-2-naphthyl, 6-ethyl-2-naphthyl,6,7-dimethyl-1-naphthyl, 6-isopropyl-2-naphthyl, 5-chloro-1-naphthyl,6-chloro-2-naphthyl, 6-bromo-1-naphthyl, 5-hydroxy-1-naphthyl,7-hydroxy-2-naphthyl, 5-dimethylamino-1-naphthyl,5-dimethylamino-2-naphthyl, 5-diethylamino-1-napththyl,6-dimethylamino-1-naphthyl and 6-dimethylamino-2-naphthyl.

Suitable R₂ groups in the above formula (I) are propyl, butyl, isobutyl,pentyl, hexyl, octyl, 2-methoxyethyl, 2-ethoxyethyl, 3-methoxypropyl,2-methylthioethyl, 2-ethylthioethyl, 3-methylthiopropyl, benzyl,phenethyl, 3-phenylpropyl, cyclopropyl, cyclohexyl, cycloheptyl andcyclohexylmethyl.

Suitable R₃ groups in the above formula (I) are hydrogen, ethyl andtert-butyl.

Illustrative of suitable N² -naphthalenesulfonyl-L-argininamides ofsufficient activity are the following:

N² -(5,6,7,8-tetrahydro-1-naphthalenesulfonyl)-L-arginyl-N-butylglycine

N²-(5,6,7,8-tetrahydro-1-naphthalenesulfonyl)-L-arginyl-N-methoxyethylglycine

N²-(5,6,7,8-tetrahydro-1-naphthalenesulfonyl)-L-arginyl-N-phenethylglycine

N²-(5,6,7,8-tetrahydro-1-naphthalenesulfonyl)-L-arginyl-N-cyclohexylglycine

N² -(5,6,7,8-tetrahydro-2-naphthalenesulfonyl)-L-arginyl-N-pentylglycine

N² -(5,6,7,8-tetrahydro-2-naphthalenesulfonyl)-L-arginyl-N-benzylglycine

N²-(5,6,7,8-tetrahydro-2-naphthalenesulfonyl)-L-arginyl-N-butyl-β-alanine

N²-(5,6,7,8-tetrahydro-2-naphthalenesulfonyl)-L-arginyl-N-cyclohexylmethylglycine

N²-(5,6,7,8-tetrahydro-2-naphthalenesulfonyl)-L-arginyl-N-benzyl-β-alanine

N² -(5-chloro-1-naphthalenesulfonyl)-L-arginyl-N-methoxyethylglycine

N² -(6-chloro-2-naphthalenesulfonyl)-L-arginyl-N-methoxyethylglycine

N² -(6-bromo-1-naphthalenesulfonyl)-L-arginyl-N-butylglycine

N² -(6-methyl-2-naphthalenesulfonyl)-L-arginyl-N-pentylglycine

N² -(7-methyl-2-naphthalenesulfonyl)-L-arginyl-N-butylglycine

N² -(7-methyl-2-naphthalenesulfonyl)-L-arginyl-N-methoxyethylglycine

N² -(7-methyl-2-naphthalenesulfonyl)-L-arginyl-N-phenethylglycine

N² -(7-methyl-2-naphthalenesulfonyl)-L-arginyl-N-cyclohexylmethylglycine

N² -(7-methyl-1-naphthalenesulfonyl)-L-arginyl-N-methoxyethylglycine

N² -(6,7-dimethyl-1-naphthalenesulfonyl)-L-arginyl-N-methoxyethylglycine

N² -(1-naphthalenesulfonyl)-L-arginyl-N-methoxyethylglycine

N² -(1-naphthalensulfonyl)-L-arginyl-N-cyclohexylglycine

N² -(2-naphthalenesulfonyl)-L-arginyl-N-butylglycine

N² -(2-naphthalenesulfonyl)-L-arginyl-N-butylglycine ethyl ester

N² -(2-naphthalenesulfonyl)-L-arginyl-N-butylglycine benzyl ester

N² -(2-naphthalenesulfonyl)-L-arginyl-N-benzylglycine

N² -(2-naphthalenesulfonyl)-L-arginyl-butyl -β-alanine

N² -(2-naphthalenesulfonyl)-L-arginyl-N-benzyl-β-alanine

N² -(5-dimethylamino-2-naphthalenesulfonyl)-L-arginyl-N-butylglycine

N²-(5-dimethylamino-1-naphthalenesulfonyl)-L-arginyl-N-methoxyethylglycine

N² -(7-hydroxy-2-naphthalenesulfonyl)-N-methoxyethylglycine

Of the compounds of this invention, it will be understood that thefollowing compounds are most preferred due to their high level ofantithrombotic activity and low level of toxicity.

N² -(7-methyl-2-naphthalenesulfonyl)-L-arginyl-butylglycine

N² -(7-methyl-2-naphthalenesulfonyl)-L-arginyl-N-methoxyethylglycine

N² -(7-methyl-2-naphthalenesulfonyl)-L-arginyl-N-phenethylglycine

N²-(5,6,7,8-tetrahydro-1-naphthalenesulfonyl)-L-arginyl-N-methoxyethylglycine

N² -(6-chloro-2-naphthalenesulfonyl)-L-arginyl-N-methoxyethylglycine

N² -(6,7-dimethyl-1-naphthalenesulfonyl)-L-arginyl-N-methoxyethylglycine

N² -(5-dimethylamino-1-naphthalenesulfonyl)-L-arginyl-N-butylglycine

The pharmaceutically acceptable salts of the above compounds are ofcourse also included within the scope of this invention.

The above compounds are intended only to illustrate the variety ofstructures which can be used in the process of this invention, and theabove listing is not to be construed as limiting the scope of theinvention.

For the preparation of the compounds of this invention, various methodscan be employed depending upon the particular starting materials and/orintermediates involved. Successful preparation of these compounds ispossible by way of several synthetic routes which are outlined below.

a. Condensation of an L-argininamide with a naphthalenesulfonyl halide

This process may be illustrated as follows: ##STR3## In the aboveformulas, R₁, R₂, R₃ and n are as defined herein above, and X ishalogen.

The N² -naphthalenesulfonyl-L-argininamide (I) is prepared by thecondensation of an L-argininamide (II) with a substantially equimolaramount of a naphthalenesulfonyl halide (III), preferably a chloride.

The condensation reaction is generally effected in a suitablereaction-inert solvent in the presence of an excess of a base, such asan organic base (triethylamine, pyridine) or a solution of an inorganicbase (sodium hydroxide, potassium carbonate), at a temperature of 0° Cto the boiling temperature of the solvent for a period of 10 minutes to15 hours.

The preferred solvents for the condensation include benzene-diethylether, diethyl ether-water and dioxane-water.

After the reaction is complete, the formed salt is extracted with water,and the solvent is removed by such standard means as evaporation underreduced pressure to give the N² -naphthalenesulfonyl-L-argininamide (I),which can be purified by trituration or recrystallization from asuitable solvent, such as diethyl ether-tetrahydrofuran, diethylether-methanol and water-methanol, or may be chromatographed on silicagel.

The L-argininamides (II) starting materials required for thecondensation reaction can be prepared by protecting the guanidino andα-amino group of the arginine via nitration, acetylation, formylation,phthaloylation, trifluoroacetylation, p-methoxybenzyloxycarbonylation,benzoylation, benzyloxycarbonylation, tert-butoxycarbonylation ortritylation and then condensing the formed N^(G) -substituted-N²-substituted-L-arginamide with a corresponding secondary amine by such aconventional process as the acid chloride method, azide method, mixedanhydride method, activated ester method or carbodiimide method, andthereafter selectively removing the protective group.

b. Removal of the N^(G) -substituent from an N^(G) -substituted-N²-naphthalenesulfonyl-L-argininamide

This process may be illustrated as follows: ##STR4## In the aboveformulas, R₁, R₂, R₃, X and n are as defined herein above; Y" is aprotective group for the amino group, such as benzyloxycarbonyl ortert-butoxycarbonyl; and Y and Y' are hydrogen and protective groups forthe guanidino group, such as nitro, tosyl, trityl, oxycarbonyl or thelike. At least one of Y and Y' is a protective group for the guanidinogroup.

The N² -naphthalenesulfonyl-L-argininamide (I) is prepared by removingthe N^(G) -substituent from an N^(G) -substituted-N²-naphthalenesulfonyl-L-argininamide (VIII) by means of acidolysis orhydrogenolysis. The acidolysis is generally effected by contacting theN^(G) -substituted-N² -naphthalenesulfonyl-L-argininamide (VIII) and anexcess of an acid such as hydrogen fluoride, hydrogen chloride, hydrogenbromide or trifluoroacetic acid, without a solvent or in a solvent, suchas an ether (tetrahydrofuran, dioxane), an alcohol (methanol, ethanol)or acetic acid at a temperature of -10° C to 100° C, and preferably atroom temperature for a period of 30 minutes to 24 hours.

The products are isolated by evaporation of the solvent and the excessacid, or by trituration with a suitable solvent followed by filtrationand drying.

Because of the use of the excess acid, the products are generally theacid addition salts of the N² -naphthalenesulfonyl-L-argininamides (I),which can be easily converted to a free amide by neutralization.

The removal of the nitro group and the oxycarbonyl group, e.g.,benzyloxycarbonyl, p-nitrobenzyloxycarbonyl, is readily accomplished bythe hydrogenolysis. The hydrogenolysis is effected in a reaction-inertsolvent, e.g., methanol, ethanol, tetrahydrofuran or dioxane, in thepresence of a hydrogen-activating catalyst, e.g., Raney nickel,palladium, or platinum, in a hydrogen atmosphere at a temperature of 0°C to the boiling temperature of the solvent for a period of 2 hours to120 hours.

The hydrogen pressure is not critical, and atmospheric pressure issufficient.

The N² -naphthalenesulfonyl-L-argininamides (I) are isolated byfiltration of the catalyst followed by evaporation of the solvent.

The N² -naphthalenesulfonyl-L-argininamides can be purified in the samemanner as described above.

The N^(G) -substituted-N² -naphthalenesulfonyl-L-argininamides (VIII)starting materials can be prepared by condensing an N^(G)-substituted-N² -substituted arginine (IV) (generally the N²-substituent is a protective group for the amino group, such asbenzyloxycarbonyl, tert-butoxycarbonyl, or the like) and a correspondingsecondary amine (V) via the azide method, mixed anhydride method,activated ester method, carbodiimido method or the like, selectivelyremoving only the N² -substituent of an N^(G) -substituted-N²-substituted argininamide (VI) by means of catalytic hydrogenolysis oracidolysis, and then condensing the thus obtained N^(G)-substituted-L-argininamide (VII) with a naphthalenesulfonyl halide(III), preferably a chloride in the presence of a base in a solvent.These reaction conditions are as described above in the condensation ofan L-argininamide with a naphthalenesulfonyl halide, and the removal ofthe N^(G) -substituent from an N^(G) -substituted-N²-naphthalenesulfonyl-L-argininamide.

c. Condensation of an N² -naphthalenesulfonyl-L-arginyl halide with anamine

This process may be illustrated as follows: ##STR5## In the aboveformulas, R₁, R₂, R₃, X and n are as defined herein above.

The N² -naphthalenesulfonyl-L-arginamide (I) is prepared by thecondensation of an N² -naphthalenesulfonyl-L-arginyl halide (IX),preferably a chloride with at least an equimolar amount of a secondaryamine (V). The condensation reaction can be carried out without an addedsolvent. However, satisfactory results will be obtained with the use ofa solvent such as basic solvents (dimethylformamide, dimethylacetamide,etc.) or halogenated solvents (chloroform, dichloromethane, etc.).

The amount of the solvent to be used is not critical and may vary fromabout 5 to 100 times the weight of the N² -naphthalenesulfonyl-L-arginylhalide (IX). Preferred condensation reaction temperatures are in therange of from -10° C to room temperature. The reaction time is notcritical, but varies with the secondary amine (V) employed. In general,a period of from 5 minutes to 10 hours is operable.

The obtained N² -naphthalenesulfonyl-L-argininamide can be isolated andpurified in the same manner as described above.

The N² -naphthalenesulfonyl-L-arginyl halide (IX) starting materialsrequired for the condensation reaction can be prepared by reacting an N²-naphthalensulfonyl-L-arginine with at least an equimolar amount of ahalogenating agent such as thionyl chloride, phosphorous oxychloride,phosphorus trichloride, phosphorous pentachloride or phosphorustribromide. The halogenation can be carried out with or without an addedsolvent. The preferred solvents are chlorinated hydrocarbons such aschloroform and dichloromethane, and ethers such as tetrahydrofuran anddioxane.

The amount of the solvent to be used is not critical and may vary fromabout 5 to 100 times the weight of the N²-naphthalenesulfonyl-L-arginine.

Preferred reaction temperatures are in the range of -10° C to roomtemperature. The reaction time is not critical, but varies with thehalogenating agent and reaction temperature. In general, a period of 15minutes to 5 hours is operable.

d. Guanidylation of an N² -naphthalenesulfonyl-L-ornithinamide or anacid addition salt thereof

This process may be illustrated as follows: ##STR6## In the aboveformulas, R₁, R₂, R₃ and n are as defined herein above.

The N² -naphthalenesulfonyl-L-argininamide (I) is prepared byguanidylating an N² -naphthalenesulfonyl-L-ornithinamide (X) with anordinary guanidylating agents such as an O-alkylisourea,S-alkylisothiourea, 1-guanyl-3,5-dimethylpyrazole or carbodiimide. Thepreferred guanidylating agents are the O-alkylisourea and theS-alkylisothiourea.

The guanidylation of the N² -naphthalenesulfonyl-L-ornithinamide (X)with the O-alkylisourea or S-alkylisothiourea is generally effected in asolvent in the presence of a base at a temperature of from 0° C to theboiling temperature of the solvent for a period of from 30 minutes to 50hours.

Examples of the preferred base are triethylamine, pyridine, sodiumhydroxide and sodium methoxide. The base is used in an amount of 0.01 to0.1 equivalent to the N² -naphthalenesulfonyl-L-ornithinamide.

Examples of the preferred solvent are water, water-ethanol andwater-dioxane.

After the reaction is complete, the N²-naphthalenesulfonyl-L-argininamide (I) is isolated by evaporation ofthe solvent followed by removal of the excess base and the formed saltby a water wash.

It is well recognized in the art that an ester derivative of the N²-naphthalenesulfonyl-L-argininamide (I) wherein R₃ is alkyl, can beprepared from a carboxylic acid derivative of the N²-naphthalenesulfonyl-L-argininamide wherein R₃ is hydrogen, by theconventional esterification methods well known to those skilled in theart. It is also well recognized in the art that the carboxylic acidderivative can be prepared from the ester derivative by the conventionalhydrolysis or acidolysis methods. The conditions under whichesterification, hydrolysis or acidolysis would be carried out will beeach apparent to those skilled in the art.

The N² -naphthalenesulfonyl-L-argininamide (I) of this invention formsacid addition salts with any of a variety of inorganic and organicacids. Some of the N² -naphthalenesulfonyl-L-argininamide containing afree carboxy group, wherein R₃ is hydrogen, forms salts with any of avariety of inorganic and organic bases.

The product of the reactions described above can be isolated in the freeform or in the form of salts. In addition, the product can be obtainedas pharmaceutically acceptable acid addition salts by reacting one ofthe free bases with an acid, such as hydrochloric, hydrobromic,hydroiodic, nitric, sulfuric, phosphoric, acetic, citric, maleic,succinic, lactic, tartaric, gluconic, benzoic, methanesulfonic,ethanesulfonic, benzenesulfonic, p-toluenesulfonic acid or the like. Ina similar manner, the product can be obtained as pharmaceuticallyacceptable salts by reacting one of the free carboxylic acids with abase, such as sodium hydroxide, potassium hydroxide, ammonium hydroxide,triethylamine, procaine, dibenzylamine, 1-ephenamine,N,N'-dibenzylethylenediamine, N-ethylpiperidine or the like. Likewise,treatment of the salts with a base or acid results in a regeneration ofthe free amide.

As stated above, the N² -naphthalenesulfonyl-L-argininamides, and thesalts thereof of this invention are characterized by highly specificinhibitory activity against thrombin as well as their substantial lackof toxicity, and therefore these compounds are useful in thedetermination of thrombin in blood as diagnostic reagents, and/or forthe medical control or prevention of thrombosis.

The antithrombotic activities of the N²-naphthalenesulfonyl-L-argininamide of this invention were compared withthat of a known antithrombotic agent, N² -(p-tolylsulfonyl)-L-argininemethyl ester, by determining the fibrinogen coagulation time. Themeasurement of the fibrinogen coagulation time was conducted as follows:

An 0.8 ml aliquot of a fibrinogen solution, which had been prepared bydissolving 150 mg of bovine fibrinogen (Cohn fraction I) supplied byArmour Inc. in 40 ml of a borate saline buffer (pH 7.4), was mixed with0.1 ml of a borate saline buffer, pH 7.4, (control) or a sample solutionin the same buffer, and 0.1 ml of a thrombin solution (5 units/ml)supplied by Mochida Pharmaceutical Co., Ltd. was added to the solutionsin an ice bath.

Immediately after mixing, the reaction mixture was transferred from theice bath to a bath maintained at 25° C. Coagulation times were taken asthe period between the time of transference to the 25° C bath and thetime of the first appearance of fibrin threads. In the cases where nodrug samples were added, the coagulation time was 50-55 seconds. Theexperimental results are summarized in Table 1. The term "concentrationrequired to prolong the coagulation time by a factor of two" is theconcentration of an active ingredient required to prolong the normalcoagulation time 50-55 seconds to 100-110 seconds.

The concentration required to prolong the coagulation time by a factorof two for the known antithrombotic agent, N²-(p-tolysulfonyl)-L-arginine methyl ester, was 1,100 μm. The inhibitorsare shown in Table 1 by indicating R₁, R₂, R₃ and n in the formula (I)and the addition moiety. When a solution containing an N²-naphthalenesulfonyl-L-argininamide of this invention was administeredintravenously into animal bodies, the high antithrombotic activity inthe circulating blood was maintained for from one to three hours. Thehalflife for decay of the anti-thrombotic compounds of this invention incirculating blood was shown to be approximately 60 minutes; thephysiological conditions of the host animals (rat, rabbit, dog andchimpanzee) were well maintained. The experimental decrease offibrinogen in animals caused by infusion of thrombin was satisfactorilycontrolled by simultaneous infusion of the compounds of this invention.

The acute toxicity values (LD₅₀) determined by intraperitonealadministration of substances of formula (I) in mice (male, 20 g) rangefrom about 1,000 to 10,000 milligrams per kilogram of body weight.Representative LD₅₀ values, for example, for N²-(5,6,7,8-tetrahydro-1-naphthalenesulfonyl)-N-methoxyethylglycine, N²-(7-methyl-2-naphthalenesulfonyl)-N-butylglycine and N²-(6,7-dimethyl-1-naphthalenesulfonyl)-N-methoxyethylglycine are above1,500 milligrams per kilogram, respectively.

On the other hand, LD₅₀ values for N² -dansyl-N-butyl-L-argininamide andN² -dansyl-N-methyl-N-butyl-L-argininamide are 75 and 70 milligrams perkilogram, respectively.

The therapeutic agents of this invention may be administered alone or incombination with pharmaceutically acceptable carriers, the proportion ofwhich is determined by the solubility and chemical nature of thecompound, chosen route of administration and standard pharmaceuticalpractice. For example, the compounds may be injected parenterally, thatis, intramuscularly, intraveneously or subcutaneously. For parenteraladministration, the compounds may be used in the form of sterilesolutions containing other solutes, for example, sufficient saline orglucose to make the solution isotonic. The compounds may be administeredorally in the form of tablets, capsules, or granules containing suitableexcipients such as starch, lactose, white sugar and the like. Thecompounds may be administered sublingually in the form of troches orlozenges in which each active ingredient is mixed with sugar or cornsyrups, flavoring agents and dyes, and then dehydrated sufficiently tomake the mixture suitable for pressing into solid form. The compoundsmay be administered orally in the form of solutions which may containcoloring and flavoring agents.

Physicians will determine the dosage of the present therapeutic agentswhich will be most suitable, and dosages vary with the mode ofadministration and the particular compound chosen. In addition, thedosage will vary with the particular patient under treatment.

When the composition is administered orally, a larger quantitity of theactive agent will be required to produce the same effect as caused witha smaller quantity given parenterally. The therapeutic dosage isgenerally 10-50 mg/kg of active ingredient parenterally, 10-500 mg/kgorally per day.

Having generally described the invention, a more complete understandingcan be obtained by reference to certain specific examples, which areincluded for purposes of illustration only and are not intended to belimiting unless otherwise specified.

EXAMPLE 1

To a solution of 3.00 g of N^(G) -nitro-N²-(5,6,7,8-tetrahydro-2-naphthalenesulfonyl)-L-arginyl-N-cyclohexylmethylglycinebenzyl ester in 50 ml of ethanol and 0.5 ml of acetic acid was added 0.5g of palladium-black and then the mixture was shaken in a hydrogenatmosphere for 100 hours at room temperature. At the end of this period,the ethanol solution was filtered to remove the catalyst and evaporatedto dryness. The residue was washed several times with dry diethyl etherand chromatographed on 80 ml of Daiaion ® SK 102 ion exchange resin(200-300 mesh, H⁺ form, manufactured by Mitsubishi Chemical IndustriesLimited) packed in water, washed with water and eluted with 3% ammoniumhydroxide solution. The fraction eluted from 3% ammonium hydroxidesolution was evaporated to dryness to give 2.07 g (87%) of N²-(5,6,7,8-tetrahydro-2-naphthalenesulfonyl)-L-arginyl-N-cyclohexylmethylglycineas a powder.

M.P. 170°-173° C (IR(KBr): 3,335, 1,630 cm⁻¹.

Analysis -- Calcd. for C₂₅ H₃₉ N₅ O₅ S (percent): C, 57.56; H, 7.54; N,13.43. Found (percent): C, 57.41; H, 7.39; N, 13.50.

The following compounds are prepared in a similar manner.

N²-(5,6,7,8-tetrahydro-2-naphthalenesulfonyl)-L-arginyl-N-ethoxyethylglycine

N²-(5,6,7,8-tetrahydro-2-naphthalenesulfonyl)-L-arginyl-N-methoxyethylglycine

N² -(6-chloro-2-naphthalenesulfonyl)-L-arginyl-N-butylglycine

N² -(7-methyl-2-naphthalenesulfonyl)-L-arginyl-N-butyl-β-alanine

N² -(7-methyl-2-naphthalenesulfonyl)-L-arginyl-N-ethoxyethylglycine

N²-(7-methyl-2-naphthalenesulfonyl)-N-methoxyethyl-N-(3-carboxypropyl)-L-argininamide

N² -(7-ethyl-2-naphthalenesulfonyl)-L-arginyl-N-methoxyethylglycine

EXAMPLE 2

To an ice-cooled suspension of 1.0 g of N²-(2-naphthalenesulfonyl)-L-arginyl-N-butylglycine in 15 ml of ethanolwas added dropwise 0.5 ml of thionyl chloride with vigorous stirring.The reaction mixture was allowed to stand for 2 hours at roomtemperature and then refluxed for 2 hours. At the end of this period,the reaction mixture was evaporated to dryness, and the residual syrupwas treated with cold ethyl ether to give 1.02 g (90%) of N²-(2-naphthalenesulfonyl)-L-arginyl-N-butylglycine ethyl esterhydrochloride in the form of a powder.

Analysis -- Calcd. for C₂₄ H₃₅ O₅ N₅ S.HCl (percent): C, 53.17; H, 6.69;N, 12,92. Found (percent): C, 52.89; H, 6.52; N, 12.74.

EXAMPLE 3

A mixture of 1.2 g of N²-(2-naphthalenesulfonyl)-L-arginyl-N-butylglycine and 1.0 g ofp-toluenesulfonic acid monohydrate in 5 ml of benzyl alcohol and 30 mlof benzene was refluxed for 5 hours, while removing water by azeotropicdistillation. At the end of this period, the solvent was evaporated andthen 100 ml of ethyl ether was added to the residue to give 1.73 g (93%)of N² -(2-naphthalenesulfonyl) L-arginyl-N-butylglycine benzyl esterp-toluenesulfonate in the form of a powder.

Analysis -- Calcd. for C₂₉ H₃₇ O₅ N₅ S.C₇ H₈ O₃ S (percent): C, 58.44;H, 6.13; N, 9.47. Found (percent): C, 58.43; H, 6.10; N, 9.40.

Various other N² -naphthalenesulfonyl-L-argininamides or acid additionsalts thereof were synthesized in accordance with the procedure of theabove examples, and the test results are summarized in Table 1.

    TABLE 1      Compound      ##STR7##      Concentrationrequired to prolong the coagulationtime by a Preparation     Elementary analysisUpper: CalculatedLower: Found Sample     Addition     factor of two process m.p.    I.R. (KBr) No. R.sub.1 R.sub.2 R.sub.3 n     moiety (μM) (Ex. No.) (° C)  C  H      N (cm.sup.-1)                              1      ##STR8##     n-C.sub.4 H.sub.9 H 1 -- 20 1 210-213 54.8654.72 7.337.21 14.5414.27     3,3501,630      2     ##STR9##     n-C.sub.5 H.sub.11 H 1 --  1 120-130 55.7355.82 7.527.50 14.1314.01      1     3,350.630      3     ##STR10##      CH.sub.2 CH.sub.2 OCH.sub.3 H 1 -- 10 1 108-110 52.1552.216.886.71      1     14.484.52 3,300 (broad)1,630      4     ##STR11##      ##STR12##      H 1 -- 30 1 powder 58.2358.01 6.456.35 13.5813.46 3,300 (broad)1,635  5      ##STR13##      ##STR14##      H 1 --  1 powder 58.9658.91 6.666.79 13.2213.15 3,200 (broad)1,635  6      ##STR15##     n-C.sub.4 H.sub.9 H2 --  1 powder 55.7355.81 7.527.40 14.1314.10 3,300     (broad) 1,630      7     ##STR16##      ##STR17##      H 1 --  1 170-173 57.5657.41 7.547.39 13.4313.50 3,3351,630      8     ##STR18##      ##STR19##      H 1 --  1 powder 56.7856.85 7.357.29 13.8013.71 3,200 (broad)1,630  9      ##STR20##      ##STR21##      H 2 --  1 powder 58.9658.796.666.51 13.2213.19 3,300 (broad)1,630  10      ##STR22##      CH.sub.2 CH.sub.2 OCH.sub.3 H 1 --  1 142-145 49.0748.90 5.495.38     13.6313.42 3,1501,620      11     ##STR23##     n-C.sub.4 H.sub.9 H 1 --  1 powder 47.4747.29 5.435.31 12.5812.39     3,1501,630      12     ##STR24##      CH.sub.2 CH.sub.2 OCH.sub.3 H 1 --  1 powder 49.0749.12 5.495.28     13.6313.59 3,1501,630      13     ##STR25##     n-C.sub.5 H.sub.11 H 1 --  1 123-130 57.0156.88 6.986.71 13.8513.65      1     3,300,635      14     ##STR26##     n-C.sub.4 H.sub.9 H 1 -- 0.3 1 powder 56.1956.00 6.776.50 14.2514.00     3,3003,1501,630      15     ##STR27##      CH.sub.2 CH.sub.2 OCH.sub.3 H 1 -- 0.2 1 powder 53.5353.24 6.336.19     14.1913.99 3,300 (broad)1,630      16     ##STR28##      ##STR29##      H 1 -- 1 powder 60.0959.79 6.166.02 12.9312.61 3,300 (broad)1,630  17      ##STR30##      ##STR31##      H 1 -- 14 1 powder 58.7358.66 7.016.90 13.1712.91 3,3801,635  18      ##STR32##      CH.sub.2 CH.sub.2 OCH.sub.3 H 1 --  1 147-150 52.5952.31 6.106.01     14.6114.33 3,3801,640      19     ##STR33##      ##STR34##      H 1 --  1 powder 57.2356.98 6.616.33 13.9113.81 3,300 (broad)1,630  20      ##STR35##      ##STR36##      H 1 --  1 powder 58.6958.79 5.715.55 13.6913.39  3,300 (broad)3,1501,630      21     ##STR37##     n-C.sub.4 H.sub.9 H 2 --  1 powder 56.1955.95 6.776.58 14.2513.97 3,190     (broad)1,620      22     ##STR38##      CH.sub.2 CH.sub.2 OCH.sub.3 H 1 -- 20 1 130-135 53.5353.28 6.336.19     14.1913.97 3,3501,640      23     ##STR39##      CH.sub.2 CH.sub.2 OCH.sub.3 H 1 -- 10 1 152-157 54.4254.28 6.556.32     13.8013.59 3,3501,635      24     ##STR40##     n-C.sub.4 H.sub.9 H 1 -- 4 1 powder 55.3655.10 6.976.76 16.1416.07     3,3801,630      25     ##STR41##      CH.sub.2 CH.sub.2 OCH.sub.3 H 1 --  1 powder 52.8652.71 6.566.29     16.0816.07      26     ##STR42##      CH.sub.2 CH.sub.2 OCH.sub.3 H 1 -- 1 powder 50.9050.81 5.905.70     14.1313.89 3,180 (broad)1,630      27     ##STR43##      ##STR44##      H 2 --  1 powder 59.4159.22 5.955.73 13.3313.28 3,170 (broad)1,620  28      ##STR45##     n-C.sub.4      H.sub.9                                                        C.sub.2     H.sub.5 1 HCl  2 powder 53.1752.89 6.696.52 12.9212.74      29     ##STR46##     n-C.sub.4      H.sub.9     ##STR47##      1      ##STR48##       3 powder 58.4458.43 6.13 6.10 9.479.40      30     ##STR49##     n-C.sub.4 H.sub.9 H 1 --  1 powder 55.3355.26 6.546.62 14.6714.58 3,200     (broad)1,630

EXAMPLE 4 Tablets Suitable for Oral Administration

Tablets containing the ingredients indicated below may be prepared byconventional techniques,

    ______________________________________                                                               Amount per tablet                                      Ingredient             (mg)                                                   ______________________________________                                        N.sup.2 -(7-methyl-2-naphthalenesulfonyl)-                                                           250                                                     L-arginyl-N-butylglycine                                                     Lactose                140                                                    Corn starch            35                                                     Talcum                 20                                                     Magnesium stearate     5                                                      ______________________________________                                        Total                  450       mg                                           ______________________________________                                    

EXAMPLE 5 Capsules for Oral Administration

Capsules of the below were made up by thoroughly mixing together batchesof the ingredients and filling hard gelatin capsules with the mixture.

    ______________________________________                                                               Amount per capsule                                     Ingredient             (mg)                                                   ______________________________________                                        N.sup.2 -(7-methyl-2-naphthalenesulfonyl)-                                                           250                                                     L-arginyl-N-butylglycine                                                     Lactose                250                                                    ______________________________________                                        Total                  500       mg                                           ______________________________________                                    

EXAMPLE 6 Sterile Solution for Infusion

The following ingredients are dissolved in water for intravenousperfusion and the resulting solution is then sterilized.

    ______________________________________                                           Ingredients           Amount (g)                                           ______________________________________                                        N.sup.2 -(7-methyl-2-naphthalenesulfonyl)-                                                             25                                                    L-arginyl-N-butylglycine                                                     Buffer system            As desired                                           Glucose                  25                                                   Distilled water          500                                                  ______________________________________                                    

Having now fully described the invention, it will be apparent to one ofordinary skill in the art that many changes and modifications can bemade thereto without departing from the spirit of the invention as setforth herein.

What is claimed as new and intended to be covered by Letters Patentis:
 1. N² -naphthalenesulfonyl-L-arginamides having the formula (I):##STR50## and the pharmaceutically acceptable salts thereof, wherein R₁is selected from the group consisting of naphthyl,5,6,7,8-tetrahydronaphthyl and naphthyl substituted with at least onesubstituent selected from the group consisting of halo, hydroxy and C₁-C₁₀ alkyl; R₂ is selected from the group consisting of C₂ -C₁₀ alkyl,C₂ -C₁₀ alkoxyalkyl, C₂ -C₁₀ alkylthioalkyl, C₇ -C₁₅ aralkyl, C₃ -C₁₀cycloalkyl and C₄ -C₁₀ cycloalkylalkyl; R₃ is selected from the groupconsisting of C₁ -C₁₀ alkyl, C₇ -C₁₂ aralkyl and C₆ -C₁₀ aryl; and n isan integer of 1,2 or
 3. 2. The compound of claim 1, wherein R₁ isselected from the group consisting of naphthyl,5,6,7,8-tetrahydronaphthyl and naphthyl substituted with at least onesubstituent selected from the group consisting of halo, hydroxy and C₁-C₅ alkyl; R₂ is selected from the group consisting of C₂ -C₆ alkyl, C₂-C₆ alkoxyalkyl, C₂ -C₆ alkoxythioalkyl, C₇ -C₁₀ aralkyl, C₃ -C₁₀cycloalkyl and C₄ -C₁₀ cycloalkylalkyl; and R₃ is selected from thegroup consisting of C₁ -C₆ alkyl, phenyl and C₇ -C₁₀ aralkyl.
 3. Thecompound of claim 2, wherein R₁ is selected from the group consisting of1-naphthyl, 2-naphthyl, 5,6,7,8-tetrahydro-1-naphthyl,5,6,7,8-tetrahydro-2-naphthyl, 6-methyl-2-naphthyl, 6-methyl-1-naphthyl,7-methyl-1-naphthyl, 7-methyl-2-naphthyl, 6-ethyl-2-naphthyl,6,7-dimethyl-1-naphthyl, 6-isopropyl-2-naphthyl, 5-chloro-1-naphthyl,6-chloro-2-naphthyl, 6-bromo-1-naphthyl, 5-hydroxy-1-naphthyl,7-hydroxy-2-naphthyl, R₂ is selected from the group consisting ofpropyl, butyl, isobutyl, pentyl, hexyl, octyl, 2-methoxyethyl,2-ethoxyethyl, 3-methoxypropyl, 2-methylthioethyl, 2-ethylthioethyl,3-methylthiopropyl, benzyl, phenethyl, 3-phenylpropyl, cyclopropyl,cyclohexyl, cycloheptyl and cyclohexylmethyl; and R₃ is ethyl ortertbutyl.
 4. A method of inhibiting activity and suppressing activationof thrombin in vivo, which comprises administering to a patient apharmaceutically effective amount of an N²-naphthalenesulfonyl-L-argininamide having the formula (I): ##STR51## orthe pharmaceutically acceptable salts thereof, wherein R₁ is selectedfrom the group consisting of naphthyl, 5,6,7,8-tetrahydronaphthyl andnaphthyl substituted with at least one substituent selected from thegroup consisting of halo, hydroxy and C₁ -C₁₀ alkyl R₂ is selected fromthe group consisting of C₂ -C₁₀ alkyl, C₂ -C₁₀ alkoxyalkyl, C₂ -C₁₀alkylthioalkyl, C₇ -C₁₅ aralkyl, C₃ -C₁₀ cycloalkyl and C₄ -C₁₀cycloalkylalkyl; R₃ is selected from the group consisting of C₁ -C₁₀alkyl, C₇ -C₁₂ aralkyl and C₆ -C₁₀ aryl; and n is an integer of 1, 2 or3.